18F2431 won't program or erase.

[keithdoxey]

HOORAY !!!!!

I have programmed all my 18F2431s and 18F4431s

Here is my response to Microchip support.

Thanks for the suggestions.

I had already tried connecting AVdd to Vdd and AVss to Vss as I noticed that they had slightly different voltages on them (5.01 and 4.97) but that didnt make any difference.

I attempted the "manual" method you suggested but didnt have the option of "Erase all before program" (MPLAB 7.30)

I then upgraded to MPLAB 7.42 and still didnt have any luck with the 2431 so I went to the 4431. Again these failed to program. A blank check revealed that they werent blank and attempts to erase the devices failed. I removed the 2.2uF capacitor and successfully erased it. I then discovered that I could now program these WITHOUT needing the capacitor.

I returned to the 2431 WITHOUT a capacitor but WITH a 1K resistor between pins 7 and 11 as that had been succesful for others on the PBP forum, SUCCESS

It would appear that the root of my problem was MPLAB 7.30 as I couldnt program 4431s either. I do need the AVdd connection to program 2431s but since upgrading to MPLAB7.42 the problem seems to be sorted.

Regards

Keith

Note to Steve: I too would appreciate a tutorial on ICSP with Picstart as it is something I have never tried. Having said that, all the PICs I use now have bootloaders but I think it would be a useful to know.

[mister_e]

OK, it's really easy.

1. You need to read your datasheet to find those MCLR, PGD, PGC and Vss pins.

2. place some jumper from the PICSTART ZIFF on the pins# you find and send them on the same pins on your PIC

3. Once the PIC is programmed, just remove the wires.

Not much. The only Extra hardware you have to add, is a 10k resistor+whatever diode on the MCLR pin. If the PGM pin of your PIC is already loaded with something it will work case not, just place a pull-down resistor on it. 10K work great

well it's a variant of something like the following taken on the melabs website...
<img src="http://melabs.com/images/icsp1.gif">

Source and more explanation here

in the past i did few adapter using some 40pins DIP socket. you make 1 of each different pic size (8,18,28,40, etc)

Also handy to use something like...
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=163&d=1104851398">

if you want to avoid this 'plug/deplug' dance.

Have fun!

[HenrikOlsson]

Keith,
Glad to here it's finally working, great!!
Let's see what the upcoming firmware does. Perhaps it will let us avoid the resistor. I think we can call this issue resolved, at last.

Steve,
Thanks a lot for the ICSP info, I will try it out next time I'm on a non-bootloader-able PIC.

Thank you both!
/Henrik Olsson.